Photographic light synchronizer



April 18 1950 w. A. STEENBERGEN 2,504,898

PHOTOGRAPHIC LIGHT SYNCHRONIZER Filed March 18, 1946 smi ,HKM www.

Patented pr. 18, 1950 UNITED STATES PATENT OFFICE PHOTOGRAPHIC LIGHTSYNCHRONIZER William A. Steenbergen, Spokane, Wash.

Application March 18, 1946, Serial No. 655,335

1 claim. 1

My invention relates to a photographic light synchronizer forsynchronizing the opening oi a camera shutter with the peak lightintensity of a flash bulb. In synchronizers oi this character the flashbulb is usually energized from a battery which also may furnish theenergy for op erating an electrical trip device that initiates releaseof the shutter. In accordance with my in vention the cable release forthe camera shutter is attached to the synchronizer unit in such a waythat the actuation of the cable release is under the control of a springthat is so mounted as to make it easy to install a spring of the properstrength and to adjust the cable release to spring connection to takecare of variations in cable travel and forces necessary to actuate thecable release for a Wide range of cameras.

I have found that the changes in springs and travel of cable release canbe made without ailecting the timing to such an extent as to interferewith proper synchronized action between the flash bulb and the shutter.Some cameras require a much stronger spring to actuate the cable releasethan others, but with my device adequate spring strength can be employedwithout upsetting the timing.

In devices of this character the drain of current from the dry cellbatteries used is an important factor. I have so constructed mysynchronizer as to obtain adequate power to trip a latch holding thecable driving spring tensioned, even with the strongest spring that maybe necessary to actuate the cable, with a very light drain on thebattery.

It is, therefore, the principal purpose of my invention to provide asimple efficient means for vactuating the camera shutter release cablein proper timed relation to the peak light output of the flash bulb.

It is a further purpose of my invention to provide, in a synchronizer ofthis character, a novel electrically operated trip mechanism for thecable release which is substantially unaffected by cable resistance, andwhich will be positive in operain section of a synchronizer involving myinvention;

Figure 2 is a similar view of a reduced scale showing the parts inchanged position;

Figure 3 is a view similar to Figure 1 but showing an all metalconstruction which is adapted to take either standard or intermediatestem flash bulbs; and

Figure 4 is a sectional view on the line 4-4 oi Figure 3.

Referring now to the drawings, my synchronizer is embodied in a casing 5which may be constructed of any suitable material. The casing 5 ispreferably cylindrical shaped and has a bracket 6 fastened thereto byscrews The bracket 5 carries an attaching screw 8 for mounting upon thecamera. The screw 8 is adapted to be secured to the camera in the usualplace for attaching the camera to a tripod. The bracket 6 has a seriesof apertures 9 to accommodate it to different size cameras.

In my synchronizer I employ ordinary dry cell batteries il! forenergizing the ilash bulb and for controlling the actuation of theshutter release cable. The shutter release cable is shown at II. It hasthe usual terminal head I2 and plunger I3, the plunger, of course,having an operating head I4. My synchronizer provides a spring poweredplunger for driving the head It in a direction to force the plunger I3to shutter trip position. The spring driven plunger is shown at I5 andit is mounted transversely on the casing 5 near the top thereof. lihecasing 5 illustrated in Figure 1 has a transparent section I5 whichcarries the iash bulb socket I'I, the plunger I5, and the electricallyenergized lcontrol means for the plunger I5.

The construction is such as to permit ready adjustment of thesynchronizer for proper travel oi' the plunger I3 to actuate theshutter. I mount a sleeve I8 on the side wall of the casing 5. In Figurel of the drawings this sleeve is secured by a threaded cap I9, the headof which is inside the casing and the stem of which threads into thesleeve I8. In the type of casing shown in Figure 3, the sleeve I8 iswelded or brazed 'to the cylindrical casing 5. The sleeve I8 is threadedon its interior throughout its length to receive another sleeve 20 thathas a ilange 2| thereon. The sleeve 20 extends beyond the flange 2I asindicated at 22 and is threaded to receive a cap 23 which serves toclamp the terminal head I2 of the shutter release cable against thesleeve portion 22. The interior of the sleeve 20 is of such size as toreadily receive the head I4 of the plunger 3 i3. A lock nut 24 holds thesleeve 2E in the desired adjusted position.

The plunger i5 has a reduced portion 23 on which a plunger actuationspring 23 is coiled. A washer '2l holds the spring 26 on the portion 25and the washer is secured by a screw 23. It is believed to be evidentthat, if the plunger it is pulled to the left from the position shown inFigure l and then released, the spring will drive it to the right andthus force the plunger i3 in the proper direction to trip the camerashutter. I nd that there are a great varin ations in cameras in thelength of travel necesw sary for the plunger i3 to trip the shutter andin the resistance of the plunger i3 and the cable release to the appliedforce for tripping the shutter. It is therefore necessary to adapt thespring force of the plunger |5 to the particular shutter releasemechanism attached by the cap 23. The spring 23 may be changed readilyto ac commodate the particular shutter release oi the camera to whichthe synchronizer is attached. The stem Eil can be moved in or out totake care of the length to which theplunger I3 is exposed beyond thehead l2. I iind that there is so little diilerence between the timenecessary to depress the plunger i3 to release the shutter by a heavyspring operating to depress a plunger having a high resistance and thetime necessary to depress the plunger by a light spring operating todepress an easily moved plunger, that this factor may be completelyignored in the timing oi the flash bulb with the shutter release. Inother words, changing of the spring 28 to accommodate a particularshutter release cable does not make it necessary to readjust thesynchroniser for proper timing.

Referring now to thev particular means by which the plunger l5 iscontrolled, it will be appreciated from the showing that the plunger iswithdrawn (or cocked)4 by hand. There is a shoulder where the reducedportion 2li ci the plunger meets the mainV portion thereof. Thisstraight shoulder is located to engage the head 3i oi a solenoid core onplunger 32 of a solenoid 33. The movement of thehe'ad 3| is directly atright angles to the movement of the plunger i3 so that there are nointermediate parts that affect the release of the plunger I5. The timingof the peak light intensity of the flash bulb with the release of theplunger after ther circuit of the solenoid 33 is closed is entirely afunction of the time in the solenoid 33 and the time lag of. the.

bulb itself. The core 32 andtheplunger l5 both rotatable so there isample wearing capacity to provide a long life for these parts.

The solenoid 33 and the flash bulb are energized from the battery I0 bydepressing a plunger taithat is mounted in a sleeve 35 on the casing 5.rlhis plunger is lnormally held in the position shown in Figures 2 and 3by a spring 33 in the sleeve 35. A contact carrying plate 3l ofinsulation is securedV on the solenoid 33 and carries a Contact strip38, the lower end of which enn gages the central terminal contact of thetop battery it. A central terminal 3S oi'. the dash bulb socket isconnected by a conductor it to a screw lli that is mounted in the innerend ci the plunger 35|. When the plunger 34 is depressed, the head ofthe screw 4| is engaged with the strip 33 to provide a path for thecurrent from the batteries over the strip 38, the screw 4|, theconductor it and the terminal 39 to the ash bulb. Likewise, a conductor42 is connected to the terminal 39 so that the coil Vof the solenoidhasone lil end connected to the center terminal of the top battery illwhen the screw 4I engages the strip 38. The return circuit for the flashbulb is through the socket its base 43, and, as shown in Figure l, overa rod 44 to the solenoid case 33. The energizing coil of the solenoidhas one end connected to the casing 33. Since the casing section it willnot conduct current to the shell 5, to which the other end of thebattery is grounded, a strip 45 of metal is connected from another screw43, that secures the solenoid to the section 6, to a screw 41 in themetallic casing 5.

In the construction shown in Figure 3, the circuit isv somewhatsimplified because of the fact that the insulating section I6 isdispensed with and the metallic casing 5 forms a return circuit from thesleeve |'l to the battery I3. In this form of invention the exposing ofthe conductor 40 where-it, is connected to the plunger 35 of insulationserves to ground one end of the conductor "lil on to the casing 5A whenthe plunger is not depressed. This means that the coil of the solenoidis short-circuited at all times except when the plunger 33 is depressed.Figure 3 illustrates the general construction Of the solenoid. Itconsists of cylindrical shell 48 of magnetic material, such as softiron, two end disks 39 and 5G of the same material, the disk 4S having apole piece 5| projecting inwardly therefrom. A non-magnetic sleeve 52 istted over the pole piece 5| and forms a. guide for the plunger 32 of thesolenoid. This construction provides a closed magnetic circuit for thesolenoid with the exception of the thin brass sleeve 52 and the gapbetween the plunger 32 and the pole piece 5|. The coil 53 of thesolenoid is wound about the sleeve 52 which has a press iit on theportion 5|. The disks 49 and 5U also are pressed into the cylinder 48 sothat a very eicient magnetic circuit for the solenoid is obtained. Thisis important in the life of the synchroniser because it cuts down thenecessary consumption oi current from the batteries and thus prolongsthe time a group of batteries may be used to operate the synchronizer.

Owing to the very simple and direct connection by the plunger i5 and thesolenoid plunger, I am able to obtain the proper timing solely by thepositioning of the plunger l5 with respect to the retracted position ofthe solenoid head 3|. It will be appreciated that if the core 32 ispulled further out, a greater build-up of magnetic force must take placein the solenoid before the core will be drawn inward. I can thereforechange the timing by the simple expedient of moving the plunger i5further away from the solenoid 33. These timing adjustments are all madein the initial manufacture of the synchronizer because the time lag ofthe ash bulb is known and my synchronizer need not be adjusted for timelag after it leaves the factory.

Figures 3 and 4 illustrate a form of mounting for the ash bulbs that isreadily adaptable to either standard bulb stems or the intermediatesize. In this `construction the cap 43 has an upwardly extending sleeve5dV which mounts a cap i355 that in turn carries the intermediate socketIl. A contact rod V53 is secured in the cap 55 by insulating members 5land nuts 58 that are threaded on the contact rod 53. This rod extendsdown and engages a screw 59 to establish a center contactfor a standardbulb. A spring 3d is mount ed on the screw 59 toinsure a good contact between the rod 53 andthe terminal 59. The sleeve 515 serves as a supportfora socket member 6| to receive' a standard flash bulb stem. Thissocket member is a split metal ring spaced from the sleeve 54 and havingconsiderable resiliency so as to make a good engagement with the bulbstem. The socket member 6l is secured to the sleeve 54 at a pointopposite the split portion by a bead of solder 62 which is poured inbetween the two parts and serves to unite them physically andelectrically.

The flash bulbs are used with reflectors so as to concentrate the lightin the proper direction. In order to mount the reflectors, I provide onthe socket Il a mounting bolt 64 :and a wing nut 65 for clamping areflector that sets down over the socket Il in place. For mounting areilector for a standard sized bulb, I provide two tubes 66 and 61 onthe casing 5 near the top thereof (see Figure 4) and I employ areilector having rods for mounting in the sleeves 56 and 6l.

I am aware of course that there are many electrically controlled releasedevices or synchronizers for controlling the shutter release in timedrelation to the peak light efficiency of the flash bulb. My devicediiiers from these devices oi which I am aware, by employing a directspring loaded shutter release plunger and controlling the shutterrelease to give the proper time lag by a. solenoid the core of Whichdirectly engages and controls the release of the spring loaded plunger.The synchronizing of the shutter release with the ilash bulb is,therefore, placed entirely within the solenoid where there is nopossibility of the timing being disturbed once it is properly set. Thedirect solenoid to the plunger connection has the additional advantagethat it reduces the amount of power necessary to control the mechanismthus lengthening the life of the batteries.

Having thus described my invention, I claim:

A sync'hronizer of the character described comprising a cylindricalcasing having means to mount a plurality of dry cell batteries therein,a solenoid mounted in the casing with its core movable axially of thecasing and having its energizing coil provided with an electricalconnection from one end thereof to the casing and the casing beingelectrically connected to one terminal of the batteries when they aremounted in the casing, a shutter release rod mounted for slidingmovement transversely of the casing in proximity to Said core, springmeans urging said rod axially in one direction for shutter release,cooperating latch means on the core and the rod for holding the rodretracted against the force of said spring, a flash bulb socket on thecasing, and means, including a switch, for electrically energizing thesolenoid and iiash bulb sirnultaneousl;7 from the batteries, said switchincluding a movable circuit closing member having an electricalconnection to the other end of the solenoid coil positioned to engagethe casing, when the switch is open to short circuit the solenoid coilexcept when it is energized.

WILLIAM A. STEENBERGEN.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 2,135,506 Hansch et al Nov. 8,1938 2,204,424 Mendelsohn June 11, 1940 2,240,813 Steenbergen May 6,1941 2,263,046 Mendelsohn et al. Nov. 18, 1941 2,292,894 Mendelsohn Aug.11, 1942 2,328,831 Mendelsohn Sept. '7, 1943 2,333,370 Graham Nov. 2,1943 FOREIGN PATENTS Number Country Date 354,291 Germany June 6, 1922

